Artemisia and Ambrosia hypersensitivity: co‐sensitization or co‐recognition?

BACKGROUND: Ragweed and mugwort have nearly identical flowering periods. Clinical and serological studies showed that ragweed and mugwort sensitization are often associated and this poses relevant clinical problems in patients for whom specific immunotherapy is warranted. OBJECTIVE: To establish whether the concurrent ragweed and mugwort pollen hypersensitivity is the result of co-sensitization or of co-recognition by using purified recombinant allergens. METHODS: Sensitization to ragweed and mugwort pollen was assessed by skin prick test (SPT) in all patients reporting allergic symptoms in August and September. IgE reactivity of sera from 42 patients (26 Amb+/Art+, 14 Amb+/Art-, and two Amb-/Art+) to ragweed and mugwort pollen extract as well as to several recombinant ragweed (rAmb a 1, rAmb a 5, rAmb a 6, rAmb a 8, rAmb a 9, and Amb a 10) and mugwort (rArt v 1, rArt v 4, rArt v 5, rArt v 6, and three EF-hand calcium-binding protein) allergens was detected by dot-blot and ELISA analyses. RESULTS: IgE reactivity of 372 weed pollen-allergic patients was studied. Mugwort reactivity was strongly associated with ragweed hypersensitivity: only 10/147 (7%) mugwort-hypersensitive patients were not sensitized to ragweed, whereas 225/362 (62%) ragweed-hypersensitive patients were not sensitized to mugwort. In vitro, 90% of ragweed-allergic patients reacted with rAmb a 1. Reactivity to other ragweed allergens ranged between 20% and 35%. Forty-six percent of the mugwort-sensitized patients recognized rArt v 1%, 25% reacted to Art v 4, Art v 5, and Art v 6, and 7% recognized the three-EF hand calcium-binding protein. Immunoblot inhibition experiments showed that pre-incubation with ragweed pollen extract only weakly decreased IgE reactivity to mugwort allergens. CONCLUSION: Patients showing both ragweed- and mugwort-positive SPT and/or RAST are co-sensitized. Future studies will establish whether IgE reactivity translates into clinical symptoms and, hence, if co-sensitized patients should undergo specific immunotherapy with extracts of both mugwort and ragweed pollen.     

Immunoglobulin E antibody reactivity to the major shrimp allergen, tropomyosin, in unexposed Orthodox Jews

BACKGROUND: Assessment of allergic (IgE antibody-mediated) reactions to foods may become complicated by cross-reactivity that can occur among certain food families and between foods and seemingly unrelated allergens. OBJECTIVE: The allergenic properties of tropomyosin (muscle-derived protein) have been recently demonstrated in invertebrates such as cockroaches, dust mites, and shrimp. In view of a possible cross-reactivity between food allergens and related allergens from animal sources, we designed a study to assess IgE antibody reactivity to the major shrimp allergen, Pen a 1, in an unexposed population of Orthodox Jews, who observe Kosher dietary laws that prohibit eating shellfish. METHODS: Nine subjects, who reacted positively by skin tests to shrimp (Penaeus setiferous), were selected for the study. Subjects (two females, seven males) ranged in age from 14 to 32 years (mean 20.4). All subjects were strictly observant of Jewish tradition and had no prior exposure to seafood (regarded as a non-Kosher food). Serum was obtained from all the subjects and tested for IgE antibody reactivity to shrimp and dust mite. RESULTS: All subjects reported symptoms of perennial allergic rhinitis, five had history of asthma, atopic dermatitis, and/or sinusitis. All had positive skin prick tests to shrimp and house dust mite (HDM) (Dermatophagoides farinae, D. pteronyssinus, or both); 2/7 subjects were positive to cockroach mix (Blattella germanica and Periplaneta americana). Sera of 4/9 subjects demonstrated specific IgE antibodies by RAST to shrimp (7.0-20.0%), 3/9 to Pen a 1 (6.3-24.1%), and 3/9 to shrimp or Pen a 1 by immunoblot. IgE binding to Pen a 1 was inhibited with either mite or cockroach extracts as demonstrated by RAST and/or immunoblot inhibition analysis. CONCLUSIONS: These studies indicate that IgE antibody reactivity to a major food allergen, shrimp, can occur in an unexposed population of individuals; some subjects allergic to HDM and/or cockroach show substantial IgE antibody reactivity to the major shrimp allergen Pen a 1 (tropomyosin). Based on inhibition with cockroach and/or dust mite extracts, this reactivity appears to be due to cross-reacting tropomyosins.     

Primary versus secondary immunoglobulin E sensitization to soy and wheat in the Multi-Centre Allergy Study cohort

Background IgE sensitization to soy and wheat is classified as ‘primary’ when generated by food ingestion and ‘secondary’ when it as a consequence of primary sensitization to cross‐reacting pollen antigens via inhalation. The age‐specific relevance of these categories of sensitization throughout childhood is unknown. Objective To monitor the natural course of IgE sensitization against common food allergens in childhood in relation to sensitization against cross‐reactive airborne allergens. Methods The German Multi‐Centre Allergy Study with follow‐up from birth to age 13 recruited initially 1314 children. IgE antibody levels against cow's milk, hen's egg, soy, wheat, mites, cat and dog dander, birch and grass pollens were tested. Longitudinal data were analysed from the 273 children with sera obtained at age 2, 5, 7 and 10 years of age. Results The point prevalence of sensitization (>1.0 kU/L) to milk and egg allergens progressively decreased from about 4% at 2 years to <1% at 10 years. By contrast, the prevalence of IgE to wheat and soy progressively increased with age, from 2% to 7% (soy) and from 2% to 9% (wheat). At 10 years of age, IgE to grass pollen was detected in 97% and 98% of the children reacting against soy and wheat, respectively; IgE to birch pollen was observed in 86% and 82% of the children reacting against soy and wheat, respectively. Early IgE sensitization to soy or wheat preceded that to grass or birch pollen in only 4% and 8% of participants sensitized to soy and wheat, respectively. Conclusion IgE sensitization to soy and wheat is relatively uncommon and mostly primary in early infancy, more frequent and mostly secondary to pollen sensitization at school age. Clinical Implications Awareness should be raised to avoid unnecessary diet restrictions due to the high frequency of clinically irrelevant, secondary sensitization to soy and wheat in schoolchildren with pollinosis.     

Comparative studies of the sensitization potential of morpholine, 2-mercaptobenzothiazole and 2 of their derivatives in guinea pigs

The aim of this study was to determine the sensitization potential of morpholine (M), 4,4'-dithiodimorpholine (DTDM), morpholinyl-mercaptobenzothiazole (MMBT) and 2-mercaptobenzothiazole (MBT) in guinea pigs. 5% and 10% DTDM, MMBT and MBT produced irritation reactions. M up to 10% failed to irritate. Sensitization tests showed that all the guinea pigs treated with DTDM and MMBT were sensitized. Cross-sensitization tests showed that 60% of the DTDM-sensitized animals reacted to challenge with MMBT; 30% of the animals sensitized to DTDM reacted to challenge with M; 80% of the MMBT-sensitized animals reacted to challenge with MBT and 10% to challenge with M; 42% of the MBT-sensitized animals reacted to MMBT. The rank order of sensitization potential in guinea pigs observed from this study is DTDM, MMBT and then MBT. It appears that the disulfide bond, sulfur linkage and the sulfhydryl group may each play a role in the sensitizing capacity of these compounds.     

In silico identification of potential new latex allergens

BACKGROUND: Allergy to latex of Hevea brasiliensis is a frequent problem. In spite of the significant progress of research, the identity and cross-reactivity of some latex allergens are unknown. OBJECTIVE: To identify, among the fully characterized latex proteins, those with a higher probability to be allergenic. METHODS: We used in silico techniques (amino acid sequence comparison and molecular modelling) to identify potential new allergens among the known proteins of H. brasiliensis. RESULTS: Cu/Zn superoxide dismutase, heat shock protein and calmodulin of H. brasiliensis show highly significant (E < 10(-9)) amino acid sequence homologies with known allergens. CONCLUSION: On the basis of our data, Cu/Zn superoxide dismutase, heat shock protein and calmodulin are the most probable allergens among fully characterized proteins of H. brasiliensis, and could potentially explain, at least in part, the multiple cross-reactivities of latex with vegetable foods and other plant-derived products. Consequently, we think that the above proteins should be particularly considered in the future laboratory and clinical research.     

Quantitative Immunoelectrophoretic Analysis of Rat Allergen Extracts

Crossed immunoelectrophoresis reference patterns were established for the antigenic constituents of rat fur, urine and saliva. Using quantitative immunoelectrophoretic techniques, extensive cross-reactivity was observed between these extracts, and with epithelia, shaved pelt, serum, faeces and dust. No major qualitative sex differences were observed, though levels of certain components differed. Constitutents of many source materials were found to show a reaction of partial identity with previously isolated rat urinary allergens; and relative skin test reactivity of a range of these extracts was associated with the amount of urinary allergen present. Material from two different rat strains had similar constituents. Rat source materials did not cross-react with the corresponding extracts from guinea pigs.     

Solubilized human thyrotrophin receptors behave as one class of high-affinity binding sites

Evidence is presented justifying the conclusion that, in contrast to the dextran-coated charcoal technique, the widely used technique of separating bound and free TSH with polyethylene glycol is inadequate and yields inaccurate results. Optimum values for the concentration of Triton X-100, pH, salts, temperature and time of incubation were established for the TSH-TSH receptor interaction. According to Scatchard analysis, soluble TSH receptors behaved as one class of binding sites. The affinity constant for this class of binding sites (K_a 1.3 × 10⁹ M^?1) is identical to that for the high-affinity binding sites found in human thyroid membranes (K_a 1.2 × 10⁹ M^?1). No low-affinity binding sites could be detected after solubilization of membrane receptors. Chromatography experiments on Sepharose CL-6B indicated that, in excess TSH, each micelle containing TSH receptors (molecular weight 150000) binds 4 [¹²⁵I]TSH molecules. These data, together with the absence of low-affinity binding sites, led to the hypothesis that high-affinity TSH binding sites may be formed by the clustering of 4 low-affinity binding sites. Cross-reactivity experiments showed that both α- and β-subunits are involved in the binding of TSH to its receptor; the TSH β-subunit showed an increased cross-reactivity with soluble receptors.     

Antigenic Variation and Cross-Reactivity in Bacteroides forsythus Clinical Isolates Detected by Western Blot

Bacteroides forsythus is one of the etiologic agents of destructive periodontal diseases. Determining which antigenic components of the bacterium are recognized in the immune response of periodontitis patients is an important step in assessing strategies for vaccine development. The aim of this study was to identify the major strain-variable and cross-reactive antigens of B. forsythus clinical isolates recognized by serum IgG from patients with early-onset rapidly progressive periodontitis. Ten patient sera with measurable IgG against antigenic components of the species were identified by Western blot. Positive sera were tested by checkerboard ELISA to identify those most responsive to strain-variable antigens in nine clinical isolates and ATCC strain 43037. Correlation analysis of the ELISA data suggested that different subsets of isolates were preferentially recognized by different sera. Western blots revealed that certain sera also recognized major shared components across all the isolates, but preferential recognition of different isolate subsets by different patients was clearly confirmed. To determine if the variable antigens recognized were nonprotein, proteinase K-digested isolates were compared to undigested controls by Western blot. The main strain-variable antigens were proteinase resistant, while proteins at 200 and 210 kDa were identified as the major shared components. Two-dimensional SDS-PAGE revealed that these proteins are the quantitatively dominant heat-modifiable components of the cell envelope. Even though variable antigens are prominent in the immune response of patients, a cross-protective vaccine based on the shared envelope proteins of B. forsythus seems feasible in light of these observations.     

Immunorecognition of anti-serotonin antibodies by using a radiolabelled ligand

Specificity of anti-serotonin antibodies to be assayed for immunocytochemical studies was tested in vitro by using a radiolabelled ligand mimicking the hapten structure. A good immunorecognition was found after coupling [3H]HT to a lysine with formaldehyde. Competition experiments by equilibrium dialysis were then carried out between [3H]HT-F-ALM and both conjugated and unconjugated indoles. The cross-reactivity ratios showed that the antibody recognition, though less specific than expected, was found suitable for immunocytochemical applications.